Journal article
Arogenate Dehydratase Isoenzymes Profoundly and Differentially Modulate Carbon Flux into Lignins
The Journal of biological chemistry, Vol.287(14), pp.11446-11459
03/30/2012
Handle:
https://hdl.handle.net/2376/107590
PMCID: PMC3322856
PMID: 22311980
Abstract
Background:
The plastid-localized arogenate dehydratase (ADT) gene family is hypothesized to differentially control carbon flux for lignin deposition, with lignin being the main contributor to lignocellulosic recalcitrance.
Results:
Single and multiple ADT knock-outs resulted in differential control over lignin content/composition.
Conclusion:
The first evidence for Phe upstream metabolism differentially controlling carbon flux into distinct secondary cell wall types was discovered.
Significance:
Upstream metabolic networks regulate secondary cell wall formation.
How carbon flux differentially occurs in vascular plants following photosynthesis for protein formation, phenylpropanoid metabolism (
i.e.
lignins), and other metabolic processes is not well understood. Our previous discovery/deduction that a six-membered arogenate dehydratase (
ADT1–6
) gene family encodes the final step in Phe biosynthesis in
Arabidopsis thaliana
raised the fascinating question whether individual ADT isoenzymes (or combinations thereof) differentially modulated carbon flux to lignins, proteins, etc. If so, unlike all other lignin pathway manipulations that target cell wall/cytosolic processes, this would be the first example of a plastid (chloroplast)-associated metabolic process influencing cell wall formation. Homozygous T-DNA insertion lines were thus obtained for five of the six ADTs and used to generate double, triple, and quadruple knockouts (KOs) in different combinations. The various mutants so obtained gave phenotypes with profound but distinct reductions in lignin amounts, encompassing a range spanning from near wild type levels to reductions of up to ∼68%. In the various KOs, there were also marked changes in guaiacyl:syringyl ratios ranging from ∼3:1 to 1:1, respectively; these changes were attributed to differential carbon flux into vascular bundles
versus
that into fiber cells. Laser microscope dissection/pyrolysis GC/MS, histochemical staining/lignin analyses, and
pADT
::
GUS
localization indicated that ADT5 preferentially affects carbon flux into the vascular bundles, whereas the
adt3456
knock-out additionally greatly reduced carbon flux into fiber cells. This plastid-localized metabolic step can thus profoundly differentially affect carbon flux into lignins in distinct anatomical regions and provides incisive new insight into different factors affecting guaiacyl:syringyl ratios and lignin primary structure.
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Details
- Title
- Arogenate Dehydratase Isoenzymes Profoundly and Differentially Modulate Carbon Flux into Lignins
- Creators
- Oliver R. A Corea - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Chanyoung Ki - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Claudia L Cardenas - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Sung-Jin Kim - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Sarah E Brewer - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Ann M Patten - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Laurence B Davin - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340Norman G Lewis - From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340
- Publication Details
- The Journal of biological chemistry, Vol.287(14), pp.11446-11459
- Academic Unit
- Biological Chemistry, Institute of
- Publisher
- American Society for Biochemistry and Molecular Biology; 9650 Rockville Pike, Bethesda, MD 20814, U.S.A
- Identifiers
- 99900547255101842
- Language
- English
- Resource Type
- Journal article